A new study has shown that killer whales along the Norwegian coast also eat seals, and these seal-eating whales are really polluted. They have up to four times the levels of the pollutant PCB in their blubber than other whales in the population that just eat fish, and levels of mercury in the skin are twice as high. Killer whales in other parts of the world can eat octopus, cod, rays and sharks, and pods of killer whales can even attack larger whales. But along the Norwegian coast, it seems that fish and seal make up the most important parts of the diet.